Sunlight readable HMIs
14 March 2011
Many important operating and monitoring tasks are carried out on HMI systems installed outdoors. This can only be done safely and easily if the displays do not reflect ambient light too strongly.
The PC-based, explosion-protected operating systems from the Stahl Open HMI series can now, on request, be fitted with 15in displays that reduce glare and reflection to a minimum. This means that canopies are no longer needed to shade the screen.
The displays can be read easily even in bright sunlight, since a filter pack effectively diverts even strong incoming ambient light. The new solution is based on a combination of polarisation filters placed on top of and behind one another in front of the display.
High brightness displays, which caused thermal problems in explosion-protected systems in particular and which were similarly useless against glare, are also no longer necessary, as the new package does not require bright LEDs. Unlike any standard filters used so far, this filter pack hardly affects the image display for viewers: although the sunlight readable displays can be adjusted to up to 1,000 cd/m², they are already easily readable even in direct sunlight with a luminescence of 700 to 800 cd/m².
Certified for hazardous gas and dust explosion zones 1, 21, 2 and 22, the Open HMIs are fitted with low-energy CPUs from the Intel Atom series and consist of explosion-protected modules. These touchscreen systems can be operated in rugged environments and even at continuously extreme ambient temperatures between -30 °C and +50 °C. Numerous international certifications ensure suitability for various applications in a wide range of industries, such as the oil and gas sector, package units and the chemical and pharmaceutical industries.
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